Brake fluid; DOT 3 or DOT 4?

alphacrimedog · 10-23-2002, 08:07 PM

Since I will be redoing my entire brake system, What type of brake fluid should I be using for normal Street driving. Also, Is it safe to use non-DOT approved SS brake lines on a street application> what is the difference between DOT and non-DOT lines besides cost?

Brad Roberts · 10-23-2002, 09:07 PM

DOT:

Has bend restrictors so the braided line doesnt rub against the metal crip connector.

Non DOT:

Has NO bend restrictors.

Never (ever) had a problem with the NON DOT (since 1986)

I always use Motul. Buy anything off the shelf your heart desires.

B

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Buy the best non-silicone fluid you can afford. Perhaps even a little better than you can afford...

I am partial to ATE Super Blue and ATE Typ 200 (same fluid, gold color instead of blue). Ford Heavy Duty has a very good rep. Motul is just about the best that you can get without spending really stupid amounts of money. (I recall something like $150/liter for some of the really exotic ones.)

My "other car" usually gets Castrol GT LMA fluid. It doesn't hold up to heat as well, but it doesn't seem to absorb water as quickly as the "better" fluids.

--DD

Ron Meier · 10-24-2002, 06:27 AM

Hey Dave - other than expense, why do you shy away from silicone base brake fluid?

It has a higher boiling point (brake fade) and is less hydroscopic (less corrosion in braking system).

We used it in the rrrrrrrrrrrrace cars.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Well, it's incompatible with seals that have seen the old fluid. It also does accumulate water, but in a layer rather than absorbed throughout. The layer tends to grow things... Ick.

A biker friend of mine tells me that Harley shipped their bikes with the silicone stuff for a while, and tagged it "long-lasting" or "never replace" stuff. They found out that the water and so on was still mucking up the brakes, so they had to go to a more frequent replacement schedule than glycol-based fluid... Oops. They stopped putting silicone in the bikes shortly after that.

This is another instance of the principle, "What is good for a rrrrrrace car is often not good for a street car."

The $150/l stuff I referred to above is also bad for a street car. I recall that it had a "wet" boiling point lower than pretty much any of the quality "street" fluids mentioned above, even though the "dry" boiling point was quite a bit higher than any of the rest. It's the kind of fluid you would need to change after every weekend--great for a track car, but awful for the street.

--DD